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Saturday, 16 July 2016

Ten degrees temperature rise by 2026?

A
Global Temperature Rise Of More than Ten Degrees Celsius By 2026?

How
much have temperatures risen and how much additional warming could
eventuate over the next decade? The image on the right shows a
potential global temperature rise by 2026 from pre-industrial
levels. This rise contains a number of elements, as discussed below
from the top down.

February
2016 rise from 1900

The
magenta element at the top reflects the temperature rise since 1900.
In February 2016, it was1.62°C warmer
compared to the year 1900, so that's a rise that has already
manifested itself.

This
earlier post discusses
this in more detail, as well as additional warming that humans
caused before 1900.

Rise
from pre-industrial levels to 1900

Additional
warming was caused by humans before
1900.
Accordingly, the next (light blue) element from the top down uses
0.3°C warming to reflect anthropogenic warming from pre-industrial
levels to the year 1900.

Rise
due to carbon dioxide from 2016 to 2026

The
purple element reflects warming due to the amount of carbon dioxide
in the atmosphere by 2026. While the IEA reported that
energy-related carbon dioxide emissions had not risen over the past
few years, carbon dioxide levels in the atmosphere have continued to
rise, due to feedbacks
that are kicking in,
such as wildfires and reduced carbon sinks. Furthermore,
maximum warming occurs about one
decade after a carbon dioxide emission,
so the full warming wrath of the carbon dioxide emissions over the
past ten years is still to come. In conclusion, an extra 0.5°C
warming by 2026 seems possible due to carbon dioxide.

Removal
of aerosols masking effect

With
dramatic cuts in emissions, there will also be a dramatic fall in
aerosols that currently mask the full warming of greenhouse gases.
From 1850 to 2010, anthropogenic aerosols brought about a decrease
of ∼2.53 K, says a recent
paper.
While on the one hand not all of the aerosols masking effect may be
removed over the next ten years, there now are a lot more aerosols
than in 2010. A 2.5°C warming due to removal of part of the
aerosols masking effect therefore seems well possible by the year
2026.

Albedo
changes in the Arctic

Warming
due to Arctic snow and ice loss may well exceed 2 W per square
meter, i.e. it could more than double the net warming now caused by
all emissions by people of the world, calculatedProfessor
Peter Wadhams in 2012.
A 1.6°C warming due to albedo changes (i.e. decline of both Arctic
sea ice and snow and ice cover on land) therefore seems well
possible by the years 2026.

Methane
eruptions from the seafloor

".
. we consider release of up to 50 Gt of predicted amount of hydrate
storage as highly possible for abrupt release at any time," Dr.
Natalia Shakhova et
al. wrote in a paper presented at EGU
General Assembly 2008.
Authors found that such a release would cause 1.3°C
warming by 2100.
Note that such warming from an extra 50 Gt of methane seems
conservative when considering that there now is only some
5 Gt of methane in the atmosphere,
and over a period of ten years this 5 Gt is already responsible
for more
warming than
all the carbon dioxide emitted by people since the start of the
industrial revolution. Professor Peter Wadhams co-authored
a study that
calculated that methane release from the seafloor of the Arctic
Ocean could yield 0.6°C warming of the planet in 5 years
(see video at earlier
post).
In conclusion, as temperatures keep rising, a 1.1°C warming due to
methane releases from clathrates at the seafloor of the world's
oceans seems well possible by the year 2026.

Extra
water vapor feedback

Rising
temperatures will result in more water vapor in the atmosphere (7%
more water vapor for every 1°C warming), further amplifying
warming, since water vapor is a potent greenhouse gas. Extra
water vapor will result from warming due to the above-mentioned
albedo changes in the Arctic and methane releases from the
seafloor that could strike within years and could result in huge
warming in addition to the warming that is already there now. As the
IPCC says: "Water vapour feedback acting alone
approximately doubles the warming from what it would be for
fixed water vapour. Furthermore, water vapour feedback acts to
amplify other feedbacks in models, such as cloud feedback and ice
albedo feedback. If cloud feedback is strongly positive, the water
vapour feedback can lead to 3.5 times as much warming as would be
the case if water vapour concentration were held fixed", according
to the IPCC.
Given a possible additional warming of 2.7°C due to just two
elements, i.e. Arctic albedo changes and seafloor methane, an
additional warming over the next decade of 2.1°C due to extra
water vapor in the atmosphere therefore does seem well possible
by the year 2026.

Further
feedbacks

Further
feedbacks will result from interactions between the above elements.
Additional water vapor in the atmosphere and extra energy trapped in
the atmosphere will result in more intense storms and precipitation,
flooding and lightning. Flooding can cause rapid decomposition of
vegetation, resulting in strong methane releases. Furthermore,
plumes above the anvils of severe storms can bring water vapor up
into the stratosphere, contributing to the formation of cirrus
clouds that
trap a lot of heat that would otherwise be radiated away, from Earth
into space. The number of lightning strikes can be expected to
increase by
about 12% for
every 1°C of rise in global average air temperature. At 3-8 miles
hight, during the summer months, lightning activity increases NOx
by as much as 90% and ozone by more than 30%. The combination of
higher temperatures and more lightning will also cause more
wildfires, resulting in emissions such as of methane and carbon
monoxide. Ozone acts as a direct greenhouse gas, while ozone and
carbon monoxide can both act to extend the lifetime of methane. Such
feedbacks may well result in an additional 0.3°C warming by the
year 2026.

Adding up all the warming associated with the
above elements results in a total potential temperature rise of more
than than 10°C or 18°F within a decade, i.e. by 2026. As said
before, this scenario assumes that no geoengineering will take place
over the next decade.

The situation is dire and calls for
comprehensive and effective action as described in the Climate
Plan.